Select Start/Programs/Ability Office 6 and right-click over say Ability Spreadsheet. Click the comaptibility tab. Make sure that No compatibility is set and the tick box is clear as shown in the following screen shot:

3. Try "clean" install

Login as a user with Admin privilages.

Uninstall Ability.

Start Windows Explorer and browse to your program directory - this is usually Program Files (Note: x64 bit Windows will use Program Files (x86).